For the benefit of those that might be trying to do it ‘on the cheap’, the official part number ASA5520-MEM-2GB= from Cisco ships with memory from Smart, part number SG5722885D8D0FO and is listed here on Smarts Web Site as being :-
UDIMM 1GB 128Mb x72 2.5V 184-pin 400MT/s PC3200 CL = 3 DDR SDRAM
Hope this is helpful to others looking to pay a little less than the £300+ charge for the official part.
** A quick note on this, installing the 2 x 1GB DIMMs will not result in a running ASA with 2.5GB available RAM. It sees it on bootup but ignores the extra 512MB once it’s running so you may aswell replace the 2 x 512MB sticks with the 2 x 1GB sticks as it gives you no benefit.
To top that, in my particular situation, my ASA went into a boot loop and didn’t start the new 8.3.1 code. To fix that I had to break out of the boot sequence into rommon and type boot asa821-k8.bin which was the image I’d upgraded from – so DON’T delete your old image before you’re sure your ASA is going to boot off it properly of you’ll have to do a tftpdnld by setting an interface with IP details and dragging an image from a TFTP server. Pain – in – the – ass. **
Since I’ve a second ASA to install/upgrade and put into Active/Standby, I’ve just re-visited this upgrade and found the following post on cisco.com
Here it states :- * Note: The maximum memory supported for the ASA-5520 and ASA-5540 is 2 Gb. If you install 4 Gb of memory in these units, they will go into a boot loop.
This I think is exactly the problem I had with my 5520, though it only had 2.5GB in it – the original 512MB plus the 2GB upgrade, so I’ll be removing the 512MB from the existing one and the new ASA when I go to do maintenance on them next week.